Model Predictive Rotor Current Control for Doubly Fed Induction Generators under Unbalanced Grid Voltages

Abstract

Under unbalanced grid condition, if negative sequence component of the grid voltage is not considered in the running system of doubly fed induction generator (DFIG), highly distorted stator currents and rotor currents will be produced. A new rotor current reference value is deduced in this paper. By analyzing the relationship between power reference and rotor currents, the reference value of rotor currents can be easily calculated without phase-locked loop (PLL). One kind of predictive current control based on the mathematical model of DFIG is proposed to directly control rotor current without any tuning work. After obtaining the analytical differentiation of the rotor currents, the reference rotor voltage is then deduced and synthesized by space vector modulation (SVM). Different from the conventional deadbeat power control with SVM (DPCSVM), all the three phase rotor currents in this method are sinusoidal and balanced when DFIG runs at unbalanced network. All simulation results for a 1.5 kW DFIG are presented to show the availability of proposed algorithm.